My fiancée and I have been living together for 1.5 years and have shared the bed almost every single night. Only once a week or so, I visit my parents and spend the night there, which is when we don't sleep in the same bed.
But one thing is very important for both of us: Same bed, but separate blankets! Once we tried one single large blanket, and it was horrible.
Another thing is that often, we have different sleep rhythms. Usually, she would fall asleep much earlier than I do, so I am reading or watching TV either in bed where she is sleeping already, or I sit at the computer in the same room. Fortunately, that doesn't bother her and doesn't disturb her sleep, just like I don't wake up when she rises early. If one of us had a much lighter sleep, this would be a problem and we probably should consider different rooms.